Defaulting to AShr without consulting the target MCAsmInfo isn't OK.
Add a flag to fix that. Keep it off for now: target migrations will
follow in separate commits.
llvm-svn: 235951
Fixes PR19582.
Previously, when an asm assignment (.set or =) was created, we would look up
the section immediately in MCSymbol::setVariableValue. This caused symbols
to receive the wrong section if the RHS of the assignment had not been seen
yet. This had a knock-on effect in the object file emitters, causing them
to emit extra symbols, or to give symbols the wrong visibility or the wrong
section. For example, in the following asm:
.data
.Llocal:
.text
leaq .Llocal1(%rip), %rdi
.Llocal1 = .Llocal2
.Llocal2 = .Llocal
the first assignment would give .Llocal1 a null section, which would never get
fixed up by the second assignment. This would cause the ELF object file emitter
to consider .Llocal1 to be an undefined symbol and give it external linkage,
even though .Llocal1 should not have been emitted at all in the object file.
Or in the following asm:
alias_to_local = Ltmp0
Ltmp0:
the Mach-O object file emitter would give the alias_to_local symbol a n_type
of N_SECT and a n_sect of 0. This is invalid under the Mach-O specification,
which requires N_SECT symbols to receive a non-zero section number if the
symbol is defined in a section in the object file.
https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/MachORuntime/#//apple_ref/c/tag/nlist
After this change we do not look up the section when the assignment is created,
but instead look it up on demand and store it in Section, which is treated
as a cache if the symbol is a variable symbol.
This change also fixes a bug in MCExpr::FindAssociatedSection. Previously,
if we saw a subtraction, we would return the first referenced section, even in
cases where we should have been returning the absolute pseudo-section. Now we
always return the absolute pseudo-section for expressions that subtract two
section-derived expressions. This isn't always correct (e.g. if one of the
sections ends up being laid out at an absolute address), but it's probably
the best we can do without more context.
This allows us to remove code in two places where we appear to have been
working around this bug, in MachObjectWriter::markAbsoluteVariableSymbols
and in X86AsmPrinter::EmitStartOfAsmFile.
Re-applies r233595 (aka D8586), which was reverted in r233898.
Differential Revision: http://reviews.llvm.org/D8798
llvm-svn: 233995
This fixes the visibility of symbols in certain edge cases involving aliases
with multiple levels of indirection.
Fixes PR19582.
Differential Revision: http://reviews.llvm.org/D8586
llvm-svn: 233595
There is something in link.exe that requires a relocation to use a
global symbol. Not doing so breaks the chrome build on windows.
This patch sets isWeak for that to work. To compensate,
we then need to look past those symbols when not creating relocations.
This patch includes an ELF test that matches GNU as behaviour.
I am still reducing the chrome build issue and will add a test
once that is done.
llvm-svn: 233318
The previous logic was to first try without relocations at all
and failing that stop on the first defined symbol.
That was inefficient and incorrect in the case part of the
expression could be simplified and another part could not
(see included test).
We now stop the evaluation when we get to a variable whose value
can change (i.e. is weak).
llvm-svn: 233187
This adds support for parsing and emitting the SBREL relocation variant for the
ARM target. Handling this relocation variant is necessary for supporting the
full ARM ELF specification. Addresses PR22128.
llvm-svn: 225595
.lower() the Name and compare only the lowecase. Removing 81 compares/lines of
code. This changes the accepted string to be mixed lower/upper case but it
should be ok.
Discussed with Jim Grosbach.
llvm-svn: 224547
Summary:
Currently, it supports generating, but not parsing, this expression.
Test added as well.
Test Plan: New test added, no regressions due to this.
Reviewers: hfinkel
Reviewed By: hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D6672
llvm-svn: 224415
Summary:
Large-model was added first. With the addition of support for multiple PIC
models in LLVM, now add small-model PIC for 32-bit PowerPC, SysV4 ABI. This
generates more optimal code, for shared libraries with less than about 16380
data objects.
Test Plan: Test cases added or updated
Reviewers: joerg, hfinkel
Reviewed By: hfinkel
Subscribers: jholewinski, mcrosier, emaste, llvm-commits
Differential Revision: http://reviews.llvm.org/D5399
llvm-svn: 221791
Nico Rieck added support for this 32-bit COFF relocation some time ago
for Win64 stuff. It appears that as an oversight, the assembly output
used "foo"@IMGREL32 instead of "foo"@IMGREL, which is what we can parse.
Sadly, there were actually tests that took in IMGREL and put out
IMGREL32, and we didn't notice the inconsistency. Oh well. Now LLVM can
assemble it's own output with slightly more fidelity.
llvm-svn: 218437
The fix itself is fairly simple: move getAccessVariant to MCValue so that we
replace the old weak expression evaluation with the far more general
EvaluateAsRelocatable.
This then requires that EvaluateAsRelocatable stop when it finds a non
trivial reference kind. And that in turn requires the ELF writer to look
harder for weak references.
Last but not least, this found a case where we were being bug by bug
compatible with gas and accepting an invalid input. I reported pr19647
to track it.
llvm-svn: 207920
When evaluating an assembly expression for a relocation, we want to
stop at MCSymbols that are in the symbol table, even if they are variables.
This is needed since the semantics may require that the relocation use them.
That is not the case when computing the value of a symbol in the symbol table.
There are no relocations in this case and we have to keep going until we hit
a section or find out that the expression doesn't have an assembly time
value.
llvm-svn: 207445
I discovered this const-hole while attempting to coalesnce the Symbol
and SymbolMap data structures. There's some pending issues with that,
but I figured this change was easy to flush early.
llvm-svn: 207124
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.
Everything will be easier with the target in-tree though, hence this
commit.
llvm-svn: 205090
Given
bar = foo + 4
.long bar
MC would eat the 4. GNU as includes it in the relocation. The rule seems to be
that a variable that defines a symbol is used in the relocation and one that
does not define a symbol is evaluated and the result included in the relocation.
Fixing this unfortunately required some other changes:
* Since the variable is now evaluated, it would prevent the ELF writer from
noticing the weakref marker the elf streamer uses. This patch then replaces
that with a VariantKind in MCSymbolRefExpr.
* Using VariantKind then requires us to look past other VariantKind to see
.weakref bar,foo
call bar@PLT
doing this also fixes
zed = foo +2
call zed@PLT
so that is a good thing.
* Looking past VariantKind means that the relocation selection has to use
the fixup instead of the target.
This is a reboot of the previous fixes for MC. I will watch the sanitizer
buildbot and wait for a build before adding back the previous fixes.
llvm-svn: 204294
This enhances the ARMAsmParser to handle .tlsdescseq directives. This is a
slightly special relocation. We must be able to generate them, but not consume
them in assembly. The relocation is meant to assist the linker in generating a
TLS descriptor sequence. The ELF target streamer is enhanced to append
additional fixups into the current segment and that is used to emit the new
R_ARM_TLS_DESCSEQ relocations.
llvm-svn: 200448
Add support for tlsdesc relocations which are part of the ABI, marked as
experimental. These relocations permit the linker to perform TLS reference
optimizations.
llvm-svn: 200447
This adds support for TLS CALL relocations. TLS CALL relocations are used to
indicate to the linker to generate appropriate entries to resolve TLS references
via an appropriate function invocation (e.g. __tls_get_addr(PLT)).
In order to accomodate the linker relaxation of the TLS access model for the
references (GD/LD -> IE, IE -> LE), the relocation addend must be incomplete.
This requires that the partial inplace value is also incomplete (i.e. 0). We
simply avoid the offset value calculation at the time of the fixup adjustment in
the ARM assembler backend.
llvm-svn: 200446
ARM symbol variants are written with parens instead of @ like this:
.word __GLOBAL_I_a(target1)
This commit adds support for parsing these symbol variants in
expressions. We introduce a new flag to MCAsmInfo that indicates the
parser should use parens to parse the symbol variant. The expression
parser is modified to look for symbol variants using parens instead
of @ when the corresponding MCAsmInfo flag is true.
The MCAsmInfo parens flag is enabled only for ARM on ELF.
By adding this flag to MCAsmInfo, we are able to get rid of
redundant ARM-specific symbol variants and use the generic variants
instead (e.g. VK_GOT instead of VK_ARM_GOT). We use the new
UseParensForSymbolVariant attribute in MCAsmInfo to correctly print
the symbol variants for arm.
To achive this we need to keep a handle to the MCAsmInfo in the
MCSymbolRefExpr class that we can check when printing the symbol
variant.
Updated Tests:
Changed case of symbol variant to match the generic kind.
test/CodeGen/ARM/tls-models.ll
test/CodeGen/ARM/tls1.ll
test/CodeGen/ARM/tls2.ll
test/CodeGen/Thumb2/tls1.ll
test/CodeGen/Thumb2/tls2.ll
PR18080
llvm-svn: 196424
In the commit message to r185476 I wrote:
>The PowerPC-specific modifiers VK_PPC_TLSGD and VK_PPC_TLSLD
>correspond exactly to the generic modifiers VK_TLSGD and VK_TLSLD.
>This causes some confusion with the asm parser, since VK_PPC_TLSGD
>is output as @tlsgd, which is then read back in as VK_TLSGD.
>
>To avoid this confusion, this patch removes the PowerPC-specific
>modifiers and uses the generic modifiers throughout. (The only
>drawback is that the generic modifiers are printed in upper case
>while the usual convention on PowerPC is to use lower-case modifiers.
>But this is just a cosmetic issue.)
This was unfortunately incorrect, there is is fact another,
serious drawback to using the default VK_TLSLD/VK_TLSGD
variant kinds: using these causes ELFObjectWriter::RelocNeedsGOT
to return true, which in turn causes the ELFObjectWriter to emit
an undefined reference to _GLOBAL_OFFSET_TABLE_.
This is a problem on powerpc64, because it uses the TOC instead
of the GOT, and the linker does not provide _GLOBAL_OFFSET_TABLE_,
so the symbol remains undefined. This means shared libraries
using TLS built with the integrated assembler are currently
broken.
While the whole RelocNeedsGOT / _GLOBAL_OFFSET_TABLE_ situation
probably ought to be properly fixed at some point, for now I'm
simply reverting the r185476 commit. Now this in turn exposes
the breakage of handling @tlsgd/@tlsld in the asm parser that
this check-in was originally intended to fix.
To avoid this regression, I'm also adding a different fix for
this problem: while common code now parses @tlsgd as VK_TLSGD,
a special hack in the asm parser translates this code to the
platform-specific VK_PPC_TLSGD that the back-end now expects.
While this is not really pretty, it's self-contained and
shouldn't hurt anything else for now. One the underlying
problem is fixed, this hack can be reverted again.
llvm-svn: 185945
The PowerPC-specific modifiers VK_PPC_TLSGD and VK_PPC_TLSLD
correspond exactly to the generic modifiers VK_TLSGD and VK_TLSLD.
This causes some confusion with the asm parser, since VK_PPC_TLSGD
is output as @tlsgd, which is then read back in as VK_TLSGD.
To avoid this confusion, this patch removes the PowerPC-specific
modifiers and uses the generic modifiers throughout. (The only
drawback is that the generic modifiers are printed in upper case
while the usual convention on PowerPC is to use lower-case modifiers.
But this is just a cosmetic issue.)
llvm-svn: 185476
This adds support for TLS data relocations and modifiers:
.quad target@dtpmod
.quad target@tprel
.quad target@dtprel
Currently exploited by the asm parser only.
llvm-svn: 185394
The current code base only supports the minimum set of tls-related
relocations and @modifiers that are necessary to support compiler-
generated code. This patch extends this to the full set defined
in the ABI (and supported by the GNU assembler) for the benefit
of the assembler parser.
llvm-svn: 184551
This adds necessary infrastructure to support the @h modifier.
Note that all required relocation types were already present
(and unused).
This patch provides support for using @h in the assembler;
it would also be possible to now use this feature in code
generated by the compiler, but this is not done yet.
llvm-svn: 184548
This renames more VK_PPC_ enums, to make them more closely reflect
the @modifier string they represent. This also prepares for adding
a bunch of new VK_PPC_ enums in upcoming patches.
For consistency, some MO_ flags related to VK_PPC_ enums are
likewise renamed.
No change in behaviour.
llvm-svn: 184547
This is another minor cleanup; to bring enum names in line
with the corresponding @modifier names, this renames:
VK_PPC_TOC -> VK_PPC_TOCBASE
VK_PPC_TOC_ENTRY -> VK_PPC_TOC16
No code change intended.
llvm-svn: 184491
When targeting the Darwin assembler, we need to generate markers ha16() and
lo16() to designate the high and low parts of a (symbolic) immediate. This
is necessary not just for plain symbols, but also for certain symbolic
expression, typically along the lines of ha16(A - B). The latter doesn't
work when simply using VariantKind flags on the symbol reference.
This is why the current back-end uses hacks (explicitly called out as such
via multiple FIXMEs) in the symbolLo/symbolHi print methods.
This patch uses target-defined MCExpr codes to represent the Darwin
ha16/lo16 constructs, following along the lines of the equivalent solution
used by the ARM back end to handle their :upper16: / :lower16: markers.
This allows us to get rid of special handling both in the symbolLo/symbolHi
print method and in the common code MCExpr::print routine. Instead, the
ha16 / lo16 markers are printed simply in a custom print routine for the
target MCExpr types. (As a result, the symbolLo/symbolHi print methods
can now replaced by a single printS16ImmOperand routine that also handles
symbolic operands.)
The patch also provides a EvaluateAsRelocatableImpl routine to handle
ha16/lo16 constructs. This is not actually used at the moment by any
in-tree code, but is provided as it makes merging into David Fang's
out-of-tree Mach-O object writer simpler.
Since there is no longer any need to treat VK_PPC_GAS_HA16 and
VK_PPC_DARWIN_HA16 differently, they are merged into a single
VK_PPC_ADDR16_HA (and likewise for the _LO16 types).
llvm-svn: 182616
This patch adds support for PowerPC platform-specific variant
kinds in MCSymbolRefExpr::getVariantKindForName, and also
adds a test case to verify they are translated to the appropriate
fixup type.
llvm-svn: 181053
Add support for the COFF relocation types IMAGE_REL_I386_DIR32NB and
IMAGE_REL_AMD64_ADDR32NB for 32- and 64-bit respectively. These are
similar to normal 4-byte relocations except that they do not include
the base address of the image.
Image-relative relocations are used for debug information (32-bit) and
SEH unwind tables (64-bit).
A new MCSymbolRef variant called 'VK_COFF_IMGREL32' is introduced to
specify such relocations. For AT&T assembly, this variant can be accessed
using the symbol suffix '@imgrel'.
llvm-svn: 179240
Colin LeMahieu